Stretch resistant therapeutic device

ABSTRACT

A vasoocclusive coil is reinforced with a stretch resistant member to improve safety during retraction of the coil. The stretch resistant member is fixedly attached at one end to the vasoocclusive coil, and the other end of the stretch resistant member is detachably mounted to an elongated pusher member to allow for placement and release of the vasoocclusive coil within the patient&#39;s vasculature.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.11/435,304, filed May 16, 2006, which is a continuation of U.S.application Ser. No. 10/202,459, filed Jul. 23, 2002, incorporated byreference in its entirety.

BACKGROUND

This invention relates generally to implantable devices forinterventional therapeutic treatment or vascular surgery, and moreparticularly concerns a stretch resistant therapeutic device such as anembolic or vasoocclusive coil and an apparatus for release anddeployment of the stretch resistant therapeutic device within apatient's vasculature.

The art and science of interventional therapy and surgery hascontinually progressed towards treatment of internal defects anddiseases by use of ever smaller incisions or access through thevasculature or body openings, in order to reduce the trauma to tissuesurrounding the treatment site. One important aspect of such treatmentsinvolves the use of catheters to place therapeutic devices at atreatment site by access through the vasculature. Examples of suchprocedures include transluminal angioplasty, placement of stents toreinforce the walls of a blood vessel or the like, and the use ofvasoocclusive devices to treat defects in the vasculature.

One specific field of interventional therapy that has been able toadvantageously use recent developments in technology is the treatment ofneurovascular defects. As smaller and more capable structures andmaterials have been developed, treatment of vascular defects in thehuman brain which were previously untreatable or representedunacceptable risks via conventional surgery have become amenable totreatment. One type of non-surgical therapy that has become advantageousfor the treatment of defects in the neurovasculature has been theplacement by way of a catheter of vasoocclusive devices such as emboliccoils in a damaged portion of a vein or artery.

Vasoocclusive devices are therapeutic devices that are placed within thevasculature of the human body, typically via a catheter, to form anembolus to block the flow of blood through a vessel making up thatportion of the vasculature, or within an aneurysm stemming from thevessel. The vasoocclusive devices can take a variety of configurations,and are generally formed of one or more elements that are larger in thedeployed configuration than when they are within the delivery catheterprior to placement. One widely used vasoocclusive device is a helicalwire coil having a deployed configuration which may be dimensioned toengage the walls of the vessels. One anatomically shaped vasoocclusivedevice that forms itself into a shape of an anatomical cavity such as ananeurysm and is made of a pre-formed strand of flexible material thatcan be a nickel-titanium alloy is known from U.S. Pat. No. 5,645,558,which is specifically incorporated by reference herein. Thatvasoocclusive device comprises one or more vasoocclusive members woundto form a generally spherical or ovoid shape in a relaxed state. Thevasoocclusive members can be a helically wound coil or a co-woven braidformed of a biocompatible material, and the device is sized and shapedto fit within a vascular cavity or vesicle, such as for treatment of ananeurysm or fistula. The vasoocclusive member can be first helicallywound or braided in a generally linear fashion, and is then wound aroundan appropriately shaped mandrel or form, and heat treated to retain theshape after removal from the heating form. Radiopacity can be providedin the vasoocclusive members by weaving in synthetic or natural fibersfilled with powdered radiopaque material, such as powdered tantalum,powdered tungsten, powdered bismuth oxide or powdered barium sulfate.

The delivery of such vasoocclusive devices can be accomplished by avariety of means, including via a catheter through which the device ispushed by a pusher to deploy the device. The vasoocclusive devices,which can have a primary shape of a coil of wire that is then formedinto a more complex secondary shape, can be produced in such a way thatthey will pass through the lumen of a catheter in a linear shape andtake on a complex shape as originally formed after being deployed intothe area of interest, such as an aneurysm. A variety of detachmentmechanisms to release the device from a pusher have been developed andare known in the art.

Vasoocclusive coils made of platinum, gold, and other ductile materialswill easily deform from their coil shape under tension, causing apotentially dangerous situation when the coil is partially in ananeurysm and partially stretched in the delivery catheter. If it isdetermined that the coil is improperly placed, or is too large, the coilwill need to be moved or replaced. However, at this stage of theprocedure, the coil can no longer be pushed, and must be slowlyretracted out of the catheter as a wire. If during this procedure thecoil breaks, an additional procedure must be performed to remove thecoil extending out of the aneurysm. It would be desirable to reinforcesuch vasoocclusive coils to provide stretch resistance to the coils toreduce the risk of the coils breaking, particularly during withdrawal ofa coil for relocation or replacement, in order to provide a safetyfactor during retraction of soft or otherwise easily stretchable coils.It would also be desirable to minimize the increase of stiffness causedby reinforcement of the coils after the coils are released in deploymentof the coils in an aneurysm so that the coils can freely transform to adesired secondary shape and conform to the dimensions of the locationbeing treated. The present invention meets these and other needs.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention provides for astretch resistant therapeutic device for release and deployment within apatient's vasculature, and an apparatus for release and deployment ofthe stretch resistant therapeutic device within a patient's vasculature,in which the therapeutic device is a vasoocclusive coil reinforced withan inner stretch resistant member to provide stretch resistance to thecoil. The incorporation of an inner stretch resistant member may alsoallow the coil to be pushed even when such a coil is partially deployed,to improve safety during retraction of the coil. The vasoocclusive coilmay be coated with one or more therapeutic agents, which may include ahydrogel. The vasoocclusive coil is reinforced by an inner stretchresistant member that is fixedly attached at one end at or near a distalend of the vasoocclusive coil, and that is detachably mounted at theother end of the vasoocclusive coil to an elongated pusher member toallow for placement and release of the vasoocclusive coil within thepatient's vasculature.

Attachment of the inner stretch resistant member toward or at the distalend of the vasoocclusive coil without connection of the inner stretchresistant member to the other end of the vasoocclusive coil minimizesthe increase of stiffness caused by reinforcement of the coil after thecoil is released for deployment. An additional advantage is that thecoil is free floating on the proximal end over the inner stretchresistant member. The inner stretch resistant member can be used toenhance radiopacity, aid in secondary shape configurations, and can beconfigured to aid desired stiffness of the coil, and can allow a softercoil to be used without stretching of the coil.

The present invention accordingly provides for a stretch resistanttherapeutic device for release and deployment within a patient'svasculature. The therapeutic device includes a vasoocclusive coildefining a lumen between proximal and distal ends of the coil, and astretch resistant member extending through the lumen of thevasoocclusive coil. The stretch resistant member is fixedly attached ata first end toward a distal end of the vasoocclusive coil, and isdetachably mountable at a second end to an elongated pusher member toallow for placement of the vasoocclusive coil within the patient'svasculature. The stretch resistant member may be formed as a ribbon,wire, braid, primary wind, or stranded material, and may be formed fromfiber, plastic or other polymer such as an ethylene-octene copolymer,polypropylene, or polyethylene, or a metal or metal alloy, such as anickel-titanium alloy, for example, or a metal which is radiopaque, suchas platinum, for example. When the stretch resistant member is formedfrom a fiber such as an ethylene-octene copolymer, polypropylene, orpolyethylene, a portion of the coil at or near the distal end of thecoil may be attached to one end of the stretch resistant member by anadhesive or by heating of the end of the fiber. In another aspect, whenthe stretch resistant member is formed of a polymer such as anethylene-octene copolymer, polypropylene, or polyethylene, the stretchresistant member may also be severable by application of heat energy tothe stretch resistant member.

The present invention also provides for an apparatus for release anddeployment of the stretch resistant therapeutic device within apatient's vasculature. The therapeutic device includes a vasoocclusivecoil defining a lumen between proximal and distal ends of thetherapeutic device. The therapeutic device may be detachably mounted tothe distal end of the pusher member, for example, by at least one loopof fiber material, by a displaced coil at the proximal end of thevasoocclusive coil, or by a loop attached at the proximal end of thetherapeutic device as a socket. The therapeutic device may by deployedmechanically or by injection.

In another aspect, the stretch resistant member is detachably mounted tothe distal end of the elongated pusher member, and means are providedfor detaching the stretch resistant member from the distal end of theelongated pusher member. In one option, a connector fiber attached tothe pusher member detachably mounts the therapeutic device to the pushermember for placement of the therapeutic device within the vasculature,and means are provided for severing the connector fiber to cause theconnector fiber to release the therapeutic device for deploying thetherapeutic device from the pusher member when a desired placement ofthe therapeutic device within the vasculature is achieved. The means forsevering the connector fiber may include an electrical resistance heaterwire or coil, when the connector fiber is formed from a thermoplasticmaterial, such as polyethylene, for example. When the stretch resistantmember is formed of a polymer such as an ethylene-octene copolymer,polypropylene, or polyethylene, the stretch resistant member can also besevered by the means for severing in the same manner.

In another option, the proximal end of the therapeutic device includes adistal therapeutic portion and a proximal stem portion, and the proximalstem portion includes at least one rounded member. A body ofconstraining material is mounted to the distal end of the elongatedpusher member, with the body of constraining material having a stressedconfiguration engaging the at least one rounded member of the stemproximal portion of the therapeutic device and a recovered configurationwithdrawn from the at least one rounded member of the proximal stemportion of the therapeutic device. In one option, the body ofconstraining material may have a tubular cross-section forming a tubularcollar extending from its proximal end to its distal end. The body ofconstraining material may be formed of a polymer such as polyurethane,or a nickel titanium alloy, for example.

These and other aspects and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings, which illustrate by way of example the features of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a stretch resistant therapeutic device andan apparatus for release and deployment of the stretch resistanttherapeutic device within a patient's vasculature according to theinvention.

FIG. 2 is a sectional view of a first alternate embodiment of a stretchresistant therapeutic device and an apparatus for release and deploymentof the stretch resistant therapeutic device within a patient'svasculature according to the invention.

FIG. 3 is a sectional view of a second alternate embodiment of a stretchresistant therapeutic device and an apparatus for release and deploymentof the stretch resistant therapeutic device within a patient'svasculature according to the invention.

FIGS. 4 and 5 are sectional views illustrating a third alternateembodiment of a stretch resistant therapeutic device and apparatus forrelease and deployment of the stretch resistant therapeutic devicewithin a patient's vasculature according to the invention, andillustrating release of the stretch resistant therapeutic device.

FIG. 6 is a sectional view of a fourth alternate embodiment of a stretchresistant therapeutic device and an apparatus for release and deploymentof the stretch resistant therapeutic device within a patient'svasculature according to the invention.

FIG. 7 is a sectional view of the stretch resistant therapeutic deviceand an apparatus for release and deployment of the stretch resistanttherapeutic device of FIG. 6, showing release of the stretch resistanttherapeutic device.

FIG. 8 is a sectional view of a fifth alternate embodiment of a stretchresistant therapeutic device and an apparatus for release and deploymentof the stretch resistant therapeutic device within a patient'svasculature according to the invention.

FIG. 9 is a sectional view of a sixth alternate embodiment of a stretchresistant therapeutic device and an apparatus for release and deploymentof the stretch resistant therapeutic device within a patient'svasculature according to the invention.

FIG. 10 is a sectional view of a seventh alternate embodiment of astretch resistant therapeutic device and an apparatus for release anddeployment of the stretch resistant therapeutic device within apatient's vasculature according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the deployment of therapeutic devices has typically beenaccomplished by using a pusher member to push such a coil through acatheter, and a variety of detachment mechanisms to release the devicefrom a pusher have been used, such coils are typically made of ductilematerials that easily deform from their coil shape once released orpartially released from the delivery catheter, so that the coils can nolonger be pushed, and withdrawing of the coils back through the cathetercan result in breakage of the coils. The present invention providesstretch resistance to such therapeutic devices to reduce the risk of thecoils breaking during withdrawal of a coil for relocation orreplacement. The present invention also minimizes the increase ofstiffness caused by reinforcement of the coils when the coils aredeployed so that the coils can freely transform to a desired secondaryshape and conform to the dimensions of the target area.

As is illustrated in the drawings, the invention is embodied in astretch resistant therapeutic device such as a vasoocclusive or emboliccoil 10 for release and deployment within a patient's vasculature. Thevasoocclusive coil has a proximal end 12 and a distal end 14, and alumen 16 extending between the proximal and distal ends. Thevasoocclusive coil may be formed from a variety of materials including,but not limited to, one or more strands of a metal or metal alloy suchas stainless steel or a nickel-titanium alloy, which may include aradiopaque strand, made of platinum, tungsten or gold, in order to serveas a marker, polymeric material such as a shape memory polymer, forexample, and coils coated with one or more therapeutic agents, such asone or more human growth modulating factors such as interleukins,transformation growth factor b, congeners of platelet derived growthfactor, and monoclonal antibodies directed against growth factors,drugs, drug producing cells, cell regeneration factors, progenitor cellsof the same type as those from the aneurysm, and progenitor cells thatare histologically different from those of the aneurysm, to acceleratethe healing process. The coil may also be coated with a hydrogel, suchas one or more hydrogels selected from organic gels and inorganic gels,and which may be combined with one or more of the therapeutic agentsdescribed above. Organic gels from which the hydrogel can be selectedinclude, by way of example and not by way of limitation, gels formedfrom polysaccharides and mucopolysaccharides including, but not limitedto hyaluronic acid, dextran, heparin sulfate, chondroitin sulfate,heparin, agar, starch, and alginate; polyaminoacids; proteins thatsupport cell growth and healing, including but not limited tofibronectin, gelatin, collagen, fibrin, pectins, albumin, ovalbumin, andpolyamino acids; collagen-hydroxyethyl-methacrylate (HEMA);polyphosphazines; polyphosphoesters; polyethylene glycol; polyethyleneoxide; polyvinyl alcohol; polyvinylpyrrolidone; polyethyloxazoline;polyethylene oxide-co-polypropyleneoxide block copolymers; PGA-PEG-PGAblock copolymers; PGA-PEG diblock copolymers; acrylates, including butnot limited to diacrylates, oligoacrylates, methacrylates,dimethacrylates and oligomethoacrylates; PEG-oligoglycolylacrylates,such as described in U.S. Pat. No. 5,626,863, which is incorporated byreference herein; carboxy alkyl celluloses, including but not limited tocarboxymethyl cellulose; partially oxidized cellulose; biodegradablepolymers including but not limited to polymers and oligomers ofglycolide, lactide, polylactic acid, polyesters of α-hydroxy acids,including lactic acid and glycolic acid, such as the poly(a-hydroxy)acids including polyglycolic acid, poly-DL-lactic, poly-L-lactic acid,and terpolymers of DL-lactide and glycolide; e-caprolactone ande-caprolactone copolymerized with polyesters; polylactones andpolycaprolactones including poly(e-caprolactone), poly(d-valerolactone)and poly(gamma-butyrolactone); polyanhydrides; polyorthoesters; otherhydroxy acids; polydioxanone; and other biologically degradable polymersthat are non-toxic or are present as metabolites in the body; as well asnon-degradable polymers such as styrene and acrolein.

Collagen-hydroxyethyl-methacrylate (HEMA) hydrogel polymer is commonlyformed from a gelled and crosslinked hydrophilic monomer solution toform a three dimensional polymeric meshwork anchoring macromolecules.Crosslinking of the hydrophilic monomer solution can be accomplished byfree radical polymerization of hydrophilic monomers, such ashydroxyethyl-methacrylate (HEMA). Hydrogel polymers formed by freeradical polymerization of monomer solutions require crosslinking to formthe three dimensional network to gel the aqueous solution. HEMA monomersolutions typically can be crosslinked to gel by dimethacrylate,although other crosslinking agents, such as ethylene glycoldimethacrylate or methylmethacrylate, can also be used duringpolymerization to modify the hydrogel. A wide variety of otherhydrophilic monomers may also be suitable.

Inorganic gels from which the hydrogel can be selected include, by wayof example and not by way of limitation, silica, alumina, and ferricoxide. In addition, an adhesive can be introduced via a catheter toinitially help seal the neck of an aneurysm, and can be selected fromthe group consisting of cyanoacrylates, gelatin/resorcinol formol,mussel adhesive protein and autologous fibrinogen adhesive. It shouldthus be apparent that the hydrogel of the invention can be of a typethat dissolves over time or one that remains as a permanent occlusiveagent within the aneurysm. A radiopaque material may be incorporatedinto the hydrogel as fine particles of a selected radiopaque metal, suchas gold or platinum.

A stretch resistant member 18 extends through the lumen of thevasoocclusive coil, and has a first or distal end 20 and a second orproximal end 22, with the first or distal end of the stretch resistantmember fixedly attached to the vasoocclusive coil. The stretch resistantmember and/or coil is detachably mounted at the second or proximal endto an elongated pusher member 24, to allow for placement of thevasoocclusive coil within the patient's vasculature. The stretchresistant member may be formed as a ribbon, wire, braid, primary wind,or stranded material, and may be formed from fiber, plastic or otherpolymer such as an ethylene-octene copolymer, polypropylene, orpolyethylene, or a metal or metal alloy, which may be a radiopaquemetal, such as platinum, for example. When the stretch resistant memberis formed from a fiber such as an ethylene-octene copolymer,polypropylene, or polyethylene, a portion at or adjacent to the distalend of the coil may be attached to one end of the stretch resistantmember by an adhesive such as a cyanoacrylate or by heating of the endof the fiber. The fiber may also be made to be radiopaque by forming thecomposition of the fiber to include a radiopaque material, such aspowdered tantalum, tungsten, bismuth oxide or barium sulfate, forexample.

As is illustrated in FIGS. 2 and 3, the stretch resistant member may bedoubled and attached at its distal end 27 toward or at the distal end ofthe coil, forming a loop 28, having a proximal end 29. Referring to FIG.1, a loop 30 formed of fiber material, metal or metal alloy, asdescribed above, may be attached to the stretch resistant member, suchas by an adhesive such as cyanoacrylate adhesive, for example. The loops28 or 30 are typically connected to a connector fiber attached to theelongated pusher member, to detachably connect the stretch resistantmember to the elongated pusher member, as will be further explainedbelow. The coil itself may be detachably mounted to the distal end ofthe pusher member, for example, by one or more loops, such as a loop offiber material 31 attached to the coil by an adhesive such ascyanoacrylate adhesive, for example, as is illustrated in FIG. 1, or bya loop 34 attached at the proximal end of the coil as a socket as shownin FIG. 2, or by a displaced end segment of the coil 36 at the proximalend of the coil as is illustrated in FIG. 3. As is shown in FIGS. 4 and5, the proximal portion 37 of the stretch resistant member may also bebonded to the pusher member, such as by adhesive or by heat bonding.Connecting both the coil and stretch resistant member to the pushermember prevents the coil from sliding over the stretch resistant memberto expose a kink point. In another alternate embodiment illustrated inFIG. 10, which is a variation of the embodiment of FIG. 3 in which thecoil may be detachably mounted to the distal end of the pusher member bya displaced end segment of the coil 36 at the proximal end of the coil,the stretch resistant member may be doubled and attached at its distalend 27 toward the distal end of the coil, forming a loop 28, having aproximal end 29 which is looped around the displaced end segment of thecoil.

The present invention also provides for an apparatus for release anddeployment of the stretch resistant therapeutic device, such as thestretch resistant vasoocclusive coil 10, within a patient's vasculature.Means 38 are provided for detachably mounting the stretch resistantmember from the distal end of the elongated pusher member. As isillustrated in FIGS. 1-3, in one aspect, a connector fiber 40 may beattached to the elongated pusher member, such as by an adhesive such asa cyanoacrylate adhesive, for example, or the connector fiber may betied to the elongated pusher member, to detachably mount thevasoocclusive coil to the pusher member for placement of thevasoocclusive coil within the vasculature, and means 42 are provided forsevering the connector fiber disposed adjacent to the connector fiber tocause the connector fiber to break and release the vasoocclusive coilfor detaching and deploying the vasoocclusive coil from the pushermember when a desired placement of the vasoocclusive coil within thevasculature is achieved. The means for severing the connector fiber mayinclude an electrical resistance heater wire or coil 44 connected viaelectrical line 46 to a control unit 48, for example, when the connectorfiber is formed from a thermoplastic material, such as polyethylene, forexample.

Referring to FIGS. 4 and 5, another embodiment of the invention providesfor a stretch resistant therapeutic device such as a vasoocclusive coil10 with a proximal end 12, a distal end 14, a lumen 16 extending betweenthe proximal and distal ends, and the stretch resistant member 18extending through the lumen of the vasoocclusive coil, with a first ordistal end 20 of the stretch resistant member fixedly attached to thetherapeutic device and the second or proximal end 22 of the stretchresistant member fixedly attached to the elongated pusher member 24. Asnoted above, the stretch resistant member may be formed as a ribbon,wire, braid, primary wind, or stranded material, and may be formed fromfiber, plastic or other polymer such as an ethylene-octene copolymer,polypropylene, or polyethylene, or a metal such as platinum, forexample. The stretch resistant member may be bonded to the pusher memberby an adhesive such as a cyanoacrylate adhesive, for example, but whenthe stretch resistant member is formed from a fiber such as anethylene-octene copolymer, polypropylene, or polyethylene, the second orproximal end of the stretch resistant member may be attached the pushermember by an adhesive such as a cyanoacrylate or by heating of thesecond or proximal end of the fiber. A connector fiber 40, such as apolyethylene fiber, may be attached to an outer portion of the elongatedpusher member as shown in FIGS. 4 and 5, by an adhesive such as acyanoacrylate adhesive, for example, or by heat bonding, or theconnector fiber may be tied to the elongated pusher member, todetachably mount the therapeutic device to the pusher member, such as bythe loop 34 attached to the coil or a displaced end segment of the coil,for placement of the therapeutic device within the vasculature. As notedabove, means 42 for severing the connector fiber may include anelectrical resistance heater wire or coil 44 connected via electricalline 46 to a control unit 48, for example.

In another embodiment illustrated in FIGS. 6 and 7, in which thetherapeutic device may be released mechanically, the proximal end of thetherapeutic device includes a distal therapeutic portion 50 and aproximal stem portion 52, and the proximal stem portion including atleast one rounded member 54. A body of constraining material 56 ismounted to the distal end of an elongated pusher member 58, with thebody of constraining material having a stressed configuration engagingthe rounded member of the stem proximal portion of the vasoocclusivecoil, as is shown in FIG. 6, and a recovered configuration withdrawnfrom the rounded member of the proximal stem portion of the therapeuticdevice, as is shown in FIG. 7. An end portion 60 at the distal end ofthe elongated pusher member may contact the rounded member of theproximal stem portion of the therapeutic device. In one option, the bodyof constraining material may have a tubular cross-section forming atubular collar extending from its proximal end 62 to its distal end 64and the end portion is located internally to the tubular collar forengaging the rounded member of the proximal stem portion of thetherapeutic device upon shape recovery of the tubular collar to dislodgethe therapeutic device from the tubular collar. The body of constrainingmaterial may be formed of a polymer such as polyurethane, or a nickeltitanium alloy, for example.

Alternatively, the therapeutic device may be released by injection, asis illustrated in FIGS. 8 and 9. Referring to FIG. 8, the proximal endof the therapeutic device includes a distal therapeutic portion 50 and aproximal stem portion 52, and the proximal stem portion including atleast one rounded member 54. A therapeutic device delivery assembly 70is provided, including an elongated flexible tubular catheter 72 havinga distal end 74. The flexible tubular catheter 72 can be formed, forexample, from polyethylene, polyethylene terephthalate, polyvinylchloride, nylon and ionomers, or other similar suitable polymers,stainless steel or nickel titanium alloy hypo tubes, and the like. Inone embodiment, the distal end of the elongated flexible tubularcatheter has a frustoconical shape. The flexible tubular catheter 72 mayinclude a tubular distal tip 76 having a proximal end 78 mounted to theouter surface of the distal end of the flexible tubular catheter, suchas by adhesive bonding, such as with a cyanoacrylate adhesive, forexample. The tubular distal tip may alternatively be heat bonded to thedistal end of the flexible tubular catheter, or may be mounted to thedistal end of the flexible tubular catheter by other suitable means. Thetubular distal tip has an inner lumen 80, and a distal end 82 with asurface defining a distal opening 84. In one aspect, the diameter of thedistal end of the tubular distal tip is smaller than the proximal end,allowing the proximal end of the therapeutic device to be capturedwithin the inner lumen of the tubular distal tip. The tubular distal tipthus has a generally frustoconical shape. Alternatively, a cylindricaltubular shape for the distal end of the catheter and the tubular distaltip may also be suitable.

The tubular distal tip is typically formed of a yieldable material thatis sufficiently rigid to retain the proximal end of the therapeuticdevice within the inner lumen of the tubular distal tip. The yieldablematerial can be, for example, a shape memory polymer, an elastomer suchas polyurethane, nylon, PEBAX polymer, Teloflex, polybutyl terephthalate(PBT), polymers available under the trade names PEBAX, Hytrel, Arnitel,Riteflex, heat shrink tubing such as polyethylene terephthalate (PET) orhigh density polyethylene (HDPE), or a shape memory metal such as nickeltitanium alloy, such as that available under the trade name NITINOL.

Means are also provided for dislodging the proximal end of thetherapeutic device captured in the inner lumen of the tubular distal tipto expel the proximal end of the therapeutic device from the distalopening of the tubular distal tip at the desired location for treatmentwithin the vasculature of a patient. As is illustrated in FIG. 8, themeans for dislodging the proximal end of the therapeutic device from theinner lumen of the tubular distal tip may be an elongated flexiblepusher member 86, such as a flexible metal wire coaxially disposedwithin the elongated flexible tubular catheter. The proximal end 88 ofthe pusher member extends from the proximal end of the elongatedflexible tubular catheter, and may include a flange or stop portion 90at the proximal end of the pusher member for limiting the movement ofthe pusher member through the delivery catheter, and the distal end 92of the pusher member is adapted to contact and dislodge the proximal endof the therapeutic device from the tubular distal tip. The distal end ofthe pusher member may also have a corresponding frustoconical shape, soas to be extendable to the distal end of the catheter to force theproximal end of the therapeutic device from the yieldable tubular distaltip to dislodge the proximal end of the therapeutic device.

An hydraulic release mechanism, may also be used for injecting thetherapeutic device. As is illustrated in FIG. 9, the tubular distal tipmay be dimensioned so as to form a tight fluid seal about the proximalend of the endoluminal device, and the means for dislodging theendoluminal device may be a syringe 94 having a plunger 96 forpressurizing a fluid, such as saline solution, for example, in a fluidchamber 98 to supply pressurized fluid through a flexible nozzle 100that can be connected to the proximal end of the elongated flexibletubular catheter for supplying the pressurized fluid within theelongated flexible tubular catheter to expel the proximal end of theendoluminal device from the tubular distal tip.

It should be recognized that other mechanisms for releasing the stretchresistant therapeutic devices may also be utilized, such as a rotationalrelease mechanism, for example. It will be apparent from the foregoingthat while particular forms of the invention have been illustrated anddescribed, various modifications can be made without departing from thespirit and scope of the invention. Accordingly, it is not intended thatthe invention be limited, except as by the appended claims.

1. An apparatus for release and deployment of a stretch resistanttherapeutic device within a patient's vasculature, comprising: avasoocclusive coil having a proximal end and a distal end, saidvasoocclusive coil defining a lumen between said proximal and distalends, said vasoocclusive coil including a distal therapeutic portion anda proximal stem portion, said proximal stem portion including at leastone rounded member; an elongated pusher member having a distal endadjacent to said proximal end of said vasoocclusive coil; a stretchresistant member extending through said lumen of said vasoocclusivecoil, said stretch resistant member being fixedly attached to saidvasoocclusive coil at the distal end of the vasoocclusive coil anddetachably mounted to the distal end of the elongated pusher member toallow for placement of the vasoocclusive coil within the patient'svasculature; a body of constraining material having a tubularcross-section forming a tubular collar mounted to the distal end of theelongated pusher member detachably retaining said at least one roundedmember, said body of constraining material having a stressedconfiguration engaging said at least one rounded member of the stemproximal portion of the vasoocclusive coil and a recovered configurationwithdrawn from said at least one rounded member of the proximal stemportion of the vasoocclusive coil; and means for dislodging saidvasoocclusive coil from said body of constraining material for detachingsaid stretch resistant member from said distal end of the elongatedpusher member, said means for dislodging said vasoocclusive coilincluding an end portion at the distal end of said elongated pushermember, said end portion contacting the proximal portion of thevasoocclusive coil when said body of constraining material changes fromsaid stressed configuration to said recovered configuration withdrawnfrom said at least one rounded member of the proximal stem portion ofthe vasoocclusive coil to dislodge said vasoocclusive coil from saidbody of constraining material.
 2. The apparatus of claim 1, wherein saidbody of constraining material is axially stressed in said stressedconfiguration to engage said proximal stem portion of the vasoocclusivecoil.
 3. The apparatus of claim 2, wherein said body of constrainingmaterial has a tubular cross-section forming a tubular collar extendingfrom its proximal end to its distal end and said end portion is locatedinternally to said tubular collar for, upon shape recovery of saidtubular collar, engaging said vasoocclusive coil to dislodge saidvasoocclusive coil from said tubular collar.
 4. The apparatus of claim1, wherein said body of constraining material is comprised of a polymer.5. The apparatus of claim 1, wherein said body of constraining materialis comprised of polyurethane.
 6. The apparatus of claim 1, wherein saidbody of constraining material is comprised of a nickel titanium alloy.7. The apparatus of claim 1, wherein said stretch resistant member isformed of a stranded material.
 8. The apparatus of claim 1, wherein saidstretch resistant member is a fiber formed from a polymer.
 9. Theapparatus of claim 1, wherein said stretch resistant member is a fiberformed from a polymer selected from the group consisting of anethylene-octene copolymer, polypropylene, and polyethylene.
 10. Theapparatus of claim 1, wherein said stretch resistant member isradiopaque.
 11. The apparatus of claim 7 or 8, wherein the stretchresistant member has first and second ends, and the vasoocclusive coilis attached to the first end of the stretch resistant member by heatingof the end of the fiber.